Composition and operation of hydrogen-selective amorphous alloy membranes

Effect of grain size on the mechanisms of plastic deformation in wrought Mg-Zn-Zr alloy revealed by acoustic emission measurements

Acoustic-emission techniques are beginning to be frequently used as a means of detecting and locating deformation and fracture processes in both metallic and non-metallic engineering structures This has happened despite a relatively poor understanding of the basic physical processes involved in the generation, propagation, and detection of acoustic-emission signals, and of the influence in metals of factors such as composition and microstructure, upon the acoustic emission from different types of deformation and fracture processes The measurement of acoustic emission, potentially, could yield much information about dynamic aspects of these processes However, it is shown that the limitations of existing acoustic-emission recording instrumentation have enabled only qualitative information to be obtained to date Even this data, however, has demonstrated that metallurgical variables greatly affect the acousticemission response of metals, and simple models to account for this are discussed

Acoustic emission for physical examination of metals

Rapidly Quenched Metals: A Bibliography, 1973–1979

The acoustic emission (AE) has been investigated systematically in tensile strained model Cu–Ge alloys with germanium concentration varied from 0.1 to 9.0 at.%. The role of various micro-structural factors in AE is discussed and the effects of solid solution hardening and stacking fault energy (SFE) on the AE power spectra are clarified. It is shown that even a small (0.1 at.%) addition of Ge changes AE significantly, whereas the dislocation AE mechanisms are similar in pure copper and its dilute alloys. It is argued that the solution hardening is a main factor governing the AE behaviour in dilute Cu–Ge solutions, resulting in the increase of lattice friction, decrease of dislocation velocity and, consequently, in reduction of the AE energy. The AE technique shows that twinning occurs from the very early stage of plastic deformation together with dislocation slip in copper alloys with germanium content as high as 5.7 at.% and the SFE is of 20 mJ m −2 and lower. Both types of AE sources—dislocation glide and twinning—have distinct features in the AE power spectra and waveforms and are discriminated with a help of data categorization technique and cluster analysis of AE.

Effect of solid solution hardening and stacking fault energy on plastic flow and acoustic emission in Cu-Ge alloys

Burst acoustic emission during the Bauschinger effect in f.c.c. and h.c.p. metals and alloys

In this note we show that the relaxation mechanism for self diffusion in solid transition metals leads quite naturally to a minimum in self diffusion coefficient at the half filled 3d, 4d and 5d-bands. We also loosely apply this concept to liquid transition metals where the relaxation is modelled as a local region of vaporization in the liquid (i.e. S(q) for large q is locally fluctuating wildly) and show that, if one can assume an Arrhenius D = D0e−φ/kT to a liquid metal, then the relaxation mechanism also predicts a minimum in self diffusion coefficint at the half filled 3d, 4d and 5d-bands for liquid transition metals. This prediction is shown to agree with the limited, scattered data for self diffusion in liquid transition metals

Predictions of the “relaxation mechanism” for self diffusion as a function of d-bandfilling in solid and liquid transition metals

Unload burst type acoustic emission during the tension cycle of the stress-strain hysteresis loop during cyclic deformation was studied and related to grain size, Bauschinger strain and stacking fault energy. The Bauschinger effect in polycrystalline 99.99% Al, 6061 and 2024A1 alloys, Cu-7.9% Al alloy, 70-30 brass and 99.95% Mg was studied for the first time at ultrasonic frequencies using acoustic emission. The relationships observed lead to a natural identification of acoustic emission the ultrasonic frequency range during cyclic deformation with the very low frequency strain burst phenomenon of Neumann. We utilize Neumann's edge dipole dissociation-trapping avalanch (EDDTA) theory for the cyclic deformation strain burst phenomenon to explain the burst acoustic emission during the Bauschinger effect reported here. A possible extension of this correspondence to non-cyclic deformation acoustic emission and its possible relation to the monatonic, non-cycle torsion millimicroplastic strain burst phenomenon of Tinder and Trzil is briefly considered.

http://ieeexplore.ieee.org/iel5/10273/32706/01533123.pdf

Burst Acoustic Emission During the Bauschinger Effect in F.C.C. and H.C.P. Metals and Alloys

Enhanced Coulomb and exchange interaction crystal fields in the modified Zener model of magnons in metallic ferromagnets

Empirical agreement of correlation between superconducting transition temperature and solute concentration in amorphous and crystalline binary transition metal alloys: Local superconductivity?

Edward Siegel

Papers

Burst acoustic emission during the Bauschinger effect in f.c.c. and h.c.p. metals and alloys

Predictions of the “relaxation mechanism” for self diffusion as a function of d-bandfilling in solid and liquid transition metals

Burst Acoustic Emission During the Bauschinger Effect in F.C.C. and H.C.P. Metals and Alloys

Enhanced Coulomb and exchange interaction crystal fields in the modified Zener model of magnons in metallic ferromagnets

Empirical agreement of correlation between superconducting transition temperature and solute concentration in amorphous and crystalline binary transition metal alloys: Local superconductivity?